As the thread title states, my B20 is causing some pretty serious shaking on the highway. I swapped it into my 94 Civic CX with an LS tranny and axles.

The axles were not brand new but the outer CV boots were replaced due to cracked rubber. There was plenty of grease in the old boots, we replaced them in the early failure stages.

This is not a vibration, let me make that very clear. This is a very severe SHAKE. It feels as though the whole car is actually moving left to right very quickly. While it's shaking it also makes a very noticeable clunking sound, hard to describe exactly.

It's not RPM related, it's a speed issue. It happens on the highway between 100-120kph (60-75 for you south of the border), it doesn't matter what gear I'm in. It doesn't shake all the time though, it starts after driving on the highway for a little while (after 10-30mins).

Letting off the gas while it's shaking almost stops it, but accelerating makes it much worse.

There is no noise or shaking over bumps or while turning either direction at city speeds.

Any thoughts? I have a few suspicions but I'd like to hear some fresh ideas before sharing what I think.

 

Could it be an unbalanced wheel? I fixed a friends car that shook, it ended up being a bent axle. Replaced them and it went away.

 

Axles. if it didn't do it prior to the axle swap.

 

Yeah I thought it could be a wheel at first but this is far beyond any unbalanced wheel I've ever experienced. I shamshed into a curb one winter and bent a steel wheel quite badly, this can't even be compared to that vibration.

 

That was my #1 suspicion, I'll have to find a way to see what side is the bad one.

I tried taking a video but the camera shook so badly it didn't really capture the issue.

 

Replace one at time, and if its not it take it back lol. Or just replace them both, it is nice to have a lifetime warranty on axles for $60

 

Axels, wheel bearings, tire balance, separated tire, loose wheel.

 

I had a similar issue to this. Ended up being the tire as well.

 

I've had a bad wheel bearing, this is another beast of a problem all together. Wheel bearings seem to have more of a deafening drone that sounds like you're driving an airplane engine. Unbalanced tires usually shake the steering wheel and make driving at high speeds almost impossible if it's bad enough. A seperated tire is sort of unlikely and not a very common problem, I'm sure it would be very evident if it was the cause. And a loose wheel would probably shake all the time, especially at city speeds. I'm still leaning towards axles.

 

sounds like a bent CV axle or a worn joint, especially since it only does it under load and not when coasting.

 

Correct me if I'm wrong but if it were your axles, wouldnt it shake at low speeds as well? And you said when you let off the gas, it goes away some? Sounds like a diff problem than axles to me.

Kev

 

at low speeds there isn't much "load" on your engine....it's like putting a mountain bike in a high gear and trying to pedal, that's "load" when it's really hard to do. Now do that to an engine with a bent CV axle and something is gonna violently shake.

 

I know what load is. But my point is, the axles are still turning. Regardless with a load or not, the axle is still working as its designed to. So at low speed he feels no shake what so ever and off the gas it tends to go away? Makes no sense IMO.

Kev

 

I'll be more specific with my details. At low speeds there is no issue whatsoever, ever. Only on the highway at 100-120 km/h does it happen and not immediately, it usually takes at least 10 mins to start. Once it starts shaking, letting off the gas does largely improve it but it doesn't go away completely. If I put load on the engine (gassing it in 5th or going up a hill) then it gets MUCH worse. I don't believe it to be engine related because it's a speed sensitive problem, rpm has no effect. I'm thinking it has to be something AFTER the transmission somewhere in the driveline. Axles seem to address all of the symptoms. It may not be a "bent" axle, could be a worn inner or outer CV joint that acts wierd when everything gets warmed up and expands a bit. At low speeds the problem might still be happening but is nearly invisible because everything isn't rotating as fast. Thoughts?

EDIT: Or could just be a shotty axle, might just be crappy altogether.

 

i was thinking wheel bearing also, put it up on a jackstand or a jack and give your front wheels wiggle to check your bearings. I doubt that's the problem but all we got right now is trial & error.

 

I'm 99% sure the wheel bearings are not the cause. It doesn't make any sense. Wheel bearings always seem to be one of two things: worn out or not worn out. In my experience wheel bearings are either always making noise regardless of speed (higher speed is obviously louder), or not making any noise at all. My cars symptoms don't follow wheel bearing rules.

 

Inner CV joint. Check for excessive clearance/play. Try jacking up the front,one wheel off the ground at a time.Run the engines and simulate the speed where the shaking occurs. Observe for abnormal movements in the cv joints/axles.

 

Ah OK. Little better lol Just for ***** and giggles, are your mounts good?

Kev

 

If something is off balance at a low speeds, it may not shake, higher speeds and something off balance is going to shake/vibrate quite a bit more. I've had an axle that was bent before and it was similar to this.

 

Sounds like what my Ford diesel does at high speeds...known as the "death wobble" Never fixed it... all I use it for is hauling my bobcat...don't really go over 50 in it... - But like someone else said...just replace axles if that's what your thinking it is...100-120 bucks for both and lifetime warranty!

 

This is a good suggestion, however when the car is jacked up off the ground the axles are no longer horizontal (like they are when the car is driving with the full weight of the car on the wheels). If I'm gassing it with one wheel off the ground, everything is relaxed including the suspension and axle. With the axle on a downward angle it may show a completely different symptom. Even if there is a slight inbalance in a tire it will make the entire car vibrate when it's off the ground spinning up to 100 km/h. Great idea, but it may not apply very well to this issue.

This may be one of the rare occurrences where throwing parts at the problem may actually be the best idea.

 

Mounts look fine. The mounts on my original D15 were SHOT and I felt it any time I touched the gas. These feel muuuch better, there is no engine movement.

I'm not a fan of the adhesive filled mounts so in the past I've cut pieces of rad hose in half and used them to fill the gaps in the mounts (small amount of silicone to keep them in place). Seems to make the mounts a bit stiffer without vibrating the cabin too much.

 

forgive me if this has been said (didnt read every post) I am gonna say ur CV is bent and/or bad wheel bearing... I had the EXACT same problem on my old 97 coupe, i meant u describe your problem to the T of what was goin on with mine a few years back...

My problem ended up being a combonation of bad wheel bearing and a bent CV (more the bent CV) from hitting a curb.... weird thing was that the car drove perfect for several months after hitting the curb, then started the violent shakes after a while

 

Hey thanks for the input, I'll be replacing the driver side axle very soon. I might do both depending on price.

I'll update this with results as soon as possible.

 

Put the jack under the lower control arms so that the axles position is the same as when it is on the ground. No harm in trying. Also when the car is in motion, the axles are continuously moving.Have somebody else peek under the car while you press on the gas.